Linking mineral deposits to speleogenetic processes in Cova des Pas de Vallgornera (Mallorca, Spain).

Abstract

[eng] Cova des Pas de Vallgornera (CPV) is the premier cave of the Balearic Archipelago. Over 74 km of passages develop within two carbonate lithofacies (reef front and back reef), which ultimately control the patterns of the cave and to some degree its mineral infilling. The diversity of speleothem-forming minerals is four times greater around or within hypogenerelated features (vents, rims, cupolas), compared to any other vadose passages in the cave. The mineralogy of speleothems (crusts, nodules, crystals, earthy masses) associated with hypogene features in the seaward upper maze of Sector F is characterized by the presence of aragonite, ankerite, huntite, clay minerals, and quartz. In the Tragus and Nord sectors, however, the dominant mineral is dolomite, along with aragonite, celestine, huntite, clay minerals, and quartz. Calcite is by far the most ubiquitous mineral throughout the cave. Detailed macroscopic and scanning electron microanalysis and imaging have permitted the investigation of textural relationships between the minerals associated with vents, rims, and vent's roof and walls. These studies along with morphological and stable isotope analyses confirm that not all minerals are connected with a hypogene stage in the cave evolution, and furthermore, none of them appears to be sulfuric acid by-products. Instead, the mineral assemblages documented in speleothems from CPV clearly support at least three speleogenetic pathways, namely seacoast mixing, ascending of warm groundwaters, and meteoric recharge (vadose). Thus, cave minerals in Cova des Pas de Vallgornera hold the keys to reconstruction and understanding of processes and conditions under which they precipitated, allowing to establish their relationship with various speleogenetic pathways